RE: Time of explosion for 28944

From: Daniel Deak (
Date: Fri Feb 23 2007 - 00:19:57 EST

  • Next message: Peter Wakelin: "SATOBS 2007 February 22"

    Good point Tony !
    Actually, when I wrote this message this afternoon here, I was too much in a
    hurry to be able to explain in details how I worked that out. So now, here
    it is.
    Starting from the beginning on Tuesday, when I first read on SeeSat about
    the strange sighting in the Australian sky and saw Rob McNaught images, it
    looked familiar to me. It looked very much like the venting of fuel from an
    Ariane rocket stage I witnessed in May 2002
    ( So I knew there was fuel involved.
    As soon as Dr Tony Phillips posted on SeeSat on Tuesady evening that the Air
    Force thought it could come from the breakup of 28944, but were not sure, I
    got the latest element set from Space Track. I used the indications about
    the observation sites on SpaceWeather to find myself the approximate
    coordinates and used SatSpy to look for the predicted trajectory as seen
    from those sites. The only precise timing I got then was the 17:15 UTC
    estimate by McNaught. I verified that 28944 did indeed make a visible pass
    near the time specified and was visible from all over Australia.
    I then used a combination of Starry Night and SatSpy to match star patterns
    in different photographs but was succesful only with Ray Palmer's. On
    Tuesday night, all I could tell is that the track seen on Ray's picture was
    indeed the track from 28944. I then tried to figure out at what time the
    start and end of the plume track were registered on the picture. I got an
    estimate of 17:10:30 for the start of the trail to about 17:16:00 UTC for
    the end although this end is quite blurred. That's what I posted Tuesday
    But yesterday (wednesday here), something bothered me. I was curious to be
    able to pinpoint the exact location for the start of the breakup given many
    pictures of the event were taken. Ray's picture intrigued me as the start of
    the trail was much smaller and sharper then the end. I asked myself if the
    start of the trail was indeed the breakup point or was it simply caused by
    the start of the long exposure (about 30 minutes). I decided to ask Ray
    about his exact coordinates and at what time was the start of the exposure.
    Here is his reply :
    "This is my geographical data at the time.
    Latitude (lat): 31°40'0"S
    Longitude (lon): 116°0'0"E
    The time my exposure started was about 1.50am and finished about 2.20am.
    This object appeared maybe ten minutes before the end of my exposure. I'd
    say around 2.05 - 2.10am."
    At Ray's location, 2.10 am is 17:10 UTC (UTC +9). So his estimate was near
    mine as to the time of the start of the trail and most important, the
    exposure was begun BEFORE the breakup. This was what lead me to presume that
    the start of the trail on Ray's picture was really the breakup point. Other
    observers told they saw the explosion occured so it must have been a sudden
    and bright event. I then analyzed Ray's picture at high magnification and
    plotted the SatSpy predicted path of 28944 in Uranometria sky atlas along
    with the photographed track. It's then that I was able to put an estimated
    time for the breakup event.
    I don't know if it's the first time a breakup is actually observed or
    photographed as it happens...
    I'm not sure either if my process to determine the breakup time is accurate,
    but from my past experiences with image interpretation and satellite
    identifications, it's the best I could do and I think it's quite reliable.
    Daniel Deak
    Webmestre, site Obsat
    Pompier, municipalite de L'Avenir, Quebec
    COSPAR site 1747 : 45.7275°N, 72.3526°W, 191 m., UTC-5:00
    Site en francais sur les satellites:
    French-language satellite web site :
    -----Message d'origine-----
    De : Tony Beresford [] 
    Envoyé : 22 février 2007 19:01
    À :
    Objet : Re: Time of explosion for 28944
    At 07:15 AM 23/02/2007, Daniel Deak wrote:
    >Hi everybody,
    >With additional information received from Ray Palmer about his 
    >photograph, I can confirm the explosion happened at 17:10:30 UTC ± 1 sec on
    Feb. 19.
    >Daniel Deak
    >Webmestre, site Obsat
    >Pompier, municipalite de L'Avenir, Quebec
    How about a little explanation Daniel, so we can have some idea how you
    worked it out.
    Tony Beresford
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